This invention relates to electrical switches generally and, in particular, to miniature electrical switches used in electronic circuits comprising components that have their leads inserted into openings of printed circuit boards or surface-mounted on printed circuit boards by automatic equipment.
Modern electronic circuits that have elements mounted on printed circuit boards often provide switch selectable options to provide different functions. It has been desired to provide a miniature electrical switch assembly having leads that fit into the openings of a printed circuit board arranged at the same standard spacing used for integrated circuit packages, or which are surface-mountable on printed circuit boards. Such a switch assembly would use a minimum of circuit board area, which is a prime consideration in board lay-out and economics. The screw switch assembly of the above-mentioned application Ser. No. 331,235 filed Dec. 16, 1981, now issued as U.S. Pat. No. 4,403,126, provides a structure readily separable into individual screw switch segments. That structure presents superior contact qualities because of the provided screw wiping clean the two opposed leads contacts.
Previously, miniature switch assemblies were mounted on printed circuit boards manually. This occurred because of the large and non-uniform dimensions of the switch assemblies, i.e. it was not economical to build special machines for inserting the prior switch assemblies into printed circuit boards or surface-mounting them on printed circuit boards. Machines were and are available, however, and are widely used, for inserting the leads of components such as transistors, resistors, capacitors and integrated circuits into openings through printed circuit boards or for surface-mounting the components thereon. The use of such automatic insertion machines or surface-mounting equipment significantly has reduced the cost of inserting or surface-mounting such components on printed circuit boards. It therefore is desirable to provide a miniature switch structure that is readily machine insertable or surface-mountable on a printed circuit board.
The assembly or prior miniature switch assemblies usually involved a plurality of parts that had to be fitted together. For example, a slide or toggle switch assembly has spring and detent parts, in addition to the contacts, that are sandwiched between top and bottom covers. It would be highly advantageous, economically, to provide a miniature switch assembly that is manufactured, carried to printed circuit board manufacturers and inserted or surface-mounted with existing equipment in or on printed circuit boards automatically by machine and with a minimum of manual handling.
Prior miniature switch assemblies, however, while providing structures and configurations providing reasonable economic manufacture, carrying and insertion of contact leads into switch bodies, can be improved. For example, the referenced patent application Ser. No. 331,235 and U.S. Pat. No. 4,027,128 both disclose screw switch assemblies that have separate contact leads that typically are press fit through vertical openings of a molded body. This requires a manual or an additional machine operation to insert the contact leads. Machine insertion is not readily possible with existing equipment and is essentially a manual operation. Slide and toggle switch assemblies present the same or increased manual or machine operations in manufacture, carrying and insertion.